Self-drilling connection anchor

ABSTRACT

A self-drilling connection anchor ( 10 ) includes an anchor tube ( 11 ), a drilling head ( 13 ) provided at the first end ( 12 ) of the anchor tube ( 11 ), an inner tube ( 15 ) arranged in the anchor tube ( 11 ) and having an interior space ( 16 ) for receiving an ejectable mass ( 30 ), a first axial, with respect to the longitudinal axis (L) defined by the anchor tube, opening ( 18 ) provided in a region of the second free end ( 14 ) that communicates with the interior space ( 16 ) of the inner tube ( 15 ), at least one outlet opening ( 20 ) provided in a region of the drilling head ( 13 ), and at least one second radial, with respect to the longitudinal axis (L), opening ( 19 ) provided in the region of the free second end ( 14 ) and communicating with the at least one outlet opening ( 20 ) via an intermediate space ( 17 ) formed between the anchor tube ( 11 ) and the inner tube ( 15 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a self-drilling connection anchorincluding an anchor tube having a first end and a free second end, adrilling head provided at the first end, an inner tube arranged in theanchor tube and having an interior space for receiving an ejectablemass, a first axial, with respect to the longitudinal axis of theanchor, opening provided in a region of the second free end of theanchor tube and which communicates with the interior space of the innertube, and at least one outlet opening provided in a region of thedrilling head.

2. Description of the Prior Art

Self-drilling anchors of the type described above are used in mining andtunneling where they serve for securing hollow spaces such as tunnels,galleries, and the like. During formation of hollow spaces, mechanicalcharacteristics and in particular the carrying capacity of rock layersare reduced. These rock layers are anchored to and are, thereby, aresecured to further, remote, undamaged rock layers with the connectionanchors.

The setting process of the known connection anchors is carried out intwo steps. In the first step, a connection anchor is drilled in the rockformation with a drilling tool. Stone, which is produced and crushed bythe drilling head of the drill anchor which is provided a the boringdirection-side end of the anchor, is removed through outlet openings,which are provided in a region of the drilling head, and theintermediate space between the bore wall and the outer circumference ofthe connection anchor. During a wet drilling process, water is fed inthe setting direction, and the removed and crushed stone is flushed out.During a dry drilling process, the removed and crushed stone isaspirated. In the second step, from the side of the connection anchorremote from the setting direction side, a chemical mass is ejected inthe direction of the bore bottom with a press-out mechanism. The mortarmass, which is located in the connection anchor, is thereby brought inthe bore from the connection anchor through the outlet opening and thedrilling head and is distributed in the intermediate space between thebore wall and the outer circumference of the anchor tube.

German Publication DE 103 36 043 A1 discloses a self-drilling connectionanchor of the type discussed above. The disclosed connection anchor hasan anchor tube at the first end of which a drilling head is provided,and a second free end. In the anchor tube, an inner tube is arranged.Between the inner tube and the anchor tube, there is provided anintermediate space extending along the longitudinal axis of the anchortube at least in some regions and formed as an annular gap. Theintermediate space provides for feeding of water during a wet drillingprocess. In the drilling head, to this end, outer openings are providedand which communicate with the intermediate space and which areconnectable with the interior space of the inner tube. In the interiorspace, an ejectable mass, which is packed in a foil bag, is located. Thechemical mass can be delivered through the outlet openings in thedrilling head. At the second, free end of the anchor tube, there isprovided a first opening that extends along the longitudinal axis andcommunicates with the intermediate space and the interior space of theinner tube.

An object of the present invention is to further improve a self-drillingconnection anchor described in the German Publication DE 103 36 043 A1.

SUMMARY OF THE INVENTION

This and other objects of the present invention, which will becomeapparent hereinafter, are achieved by providing at least one second,radial, with respect to the longitudinal axis, opening in the region ofthe free second end which communicates with at least one outlet openingvia an intermediate space formed between the anchor tube and the innertube.

By separation of the access to the intermediate space, on one hand, fromthe access to the interior space of the inner tube, on the other hand,crossing of the fed flushing water and the advanced press-out means canbe prevented. Separate feeds can be provided at the axial, first openingand the at least one radial, second opening. Thereby, conventional drilldrive motors with central flushing water feeding in which no second loopfor a high-pressure press-out media is available, can be used.

Advantageously, there are provided two opposite radial, second openingswhereby a sufficient flushing water supply is insured when theconnection anchor rotates.

Advantageously, the at least one radial, second opening is provided inthe anchor tube. This insures a good access to the radial, secondopening from outside and that it opens directly in the intermediatespace.

It is further advantageous when the at least one radial, second openingis spaced from the free second end of the anchor tube by a distancecorresponding to from 0.5 to 2 times of an anchor tube diameter.Thereby, it is achieved that common flushing water systems are usedsimultaneously with common drill motors with the central water feeding.

The novel features of the present invention, which are considered ascharacteristic for the invention, are set forth in the appended claims.The invention itself, however, both as to its construction and its modeof operation, together with additional advantages and objects thereof,will be best understood from the following detailed description ofpreferred embodiment, when read with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Single FIGURE shows a longitudinal cross-sectional view of aself-drilling connection anchor according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A self-drilling connection anchor 10 according to the present invention,which is shown in the FIGURE, includes a steel anchor tube 11 and aninner tube 15 which is formed of steel or a plastic material and isarranged in the anchor tube 11. In the interior space 16 of the innertube 15, there is arranged an ejectable mass 30 such as one-ormulti-component chemical mass and which is packed in a foil bag 31. Theanchor tube 11 has a first end 12 with a drilling head 13 insertedtherein, and a free second end 14. The anchor tube 11 defines alongitudinal axis L of the connection anchor 10. A first centeringelement 24 and a second centering element 25 axially and radially retainthe inner tube 15 in the anchor tube 11, so that the inner tube 15 canbe guided coaxially with respect to longitudinal axis L.

In the region of the free second end 14 of the anchor tube 11, there isprovided an axial, with respect to the longitudinal axis L, firstopening 18 that communicates with the interior space 16 of the innertube 15. Through this first opening 18, a pressure medium (first arrow21), e.g., water can be fed under pressure in the interior space 16,whereby the foil bag 31, which is located in the inner tube 15, isejected by a press-out member 33 displaceable in the inner tube 15between the axial first opening 18 and the foil bag. The mass 30, whichis contained in the foil bag 31, is displaced through a mixing member32, whereby the components of the mass 30 intermix. The intermixed mass30 can then be displaced in the direction of the second arrow 22 fromthe inner tube 15 or the mixing member 22 into the drilling head 13 andfurther through outlet opening 20, which are provided in the drillinghead 13, into an outer space that surrounds the connection anchor 10.

The centering element 24, 25 so position the inner tube 15 in the anchortube 11 that an intermediate space 17 in form of an annular gap isformed between the anchor tube 11 and the inner tube 15. In the regionof the free second end of the anchor tube 11, there are provided, in theanchor tube 11, two, opposite, with respect to the longitudinal axis L,radial openings 19. The radial openings 19 communicate with outletopenings 20 formed in the drilling head 13 via the intermediate space17. The intermediate space 17 provides for feeding water in case of awet drilling process. The water can flow through the radial secondopenings 19 into the intermediate space 17 (third arrow 23) and,finally, through the outlet openings 20 in the outer space of theconnection anchor 10.

The radial second openings 19 are preferably axially spaced by adistance A from the free second end 14 of the anchor tube 11. Thedistance A corresponds to form 0.5 to 2 times of the diameter D of theanchor tube 11.

It should be clear that the outlet openings 20, the intermediate space17, and the radial second openings 19 can be used for aspirating boredust during a dry drilling process.

Though the present invention was shown and described with references tothe preferred embodiment, such is merely illustrative of the presentinvention and is not to be construed as a limitation thereof and variousmodifications of the present invention will be apparent to those skilledin the art. It is therefore not intended that the present invention belimited to the disclosed embodiment or details thereof, and the presentinvention includes all variations and/or alternative embodiments withinthe spirit and scope of the present invention as defined by the appendedclaims.

1. A self-drilling connection anchor (10) for use in mining andtunneling, comprising an anchor tube (11) defining a longitudinal axis(L) and having a first end (12) and a free second end (14); a drillinghead (13) provided at the first end (12); an inner tube (15) arranged inthe anchor tube (11) and having an interior space (16) for receiving anejectable mass (30); a first axial, with respect to the longitudinalaxis (L), opening (18) provided in a region of the second free end (14)that communicates with the interior space (16) of the inner tube (15);at least one outlet opening (20) provided in a region of the drillinghead (13); and at least one second radial, with respect to thelongitudinal axis (L), opening (19) provided in the region of the freesecond end (14) of the anchor tube 11 and communicating with the atleast one outlet opening (20) via an intermediate space (17) formedbetween the anchor tube (11) and the inner tube (15).
 2. A connectionanchor according to claim 1, comprising two opposite radial secondopenings (19).
 3. A connection anchor according to claim 1, wherein theat least one second radial opening (19) is provided in the anchor tube(11).
 4. A connection anchor according to claim 1, wherein the at leastone radial second opening (19) is spaced from the free second end (14)of the anchor tube (11) by a distance (A) corresponding to from 0.5 to 2times of an anchor tube diameter (D).